What are all values in bound_box?
You will get 8 values only,

&gt;&gt;&gt; obj = bpy.context.active_object
&gt;&gt;&gt; obj.bound_box
bpy.data.objects['Cube'].bound_box

&gt;&gt;&gt; [v[:] for v in obj.bound_box]
[(-1.0, -1.0, -1.0), 
 (-1.0, -1.0, 1.0),
 (-1.0, 1.0, 1.0),
 (-1.0, 1.0, -1.0),
 (1.0, -1.0, -1.0),
 (1.0, -1.0, 1.0),
 (1.0, 1.0, 1.0),
 (1.0, 1.0, -1.0)]




for Suzanne it would be:



Here's some code I wrote about 2 years ago to get x.min, x.max, etc., and distance over the axis for x, y and z. With instructions how to use it. (I have this tucked away in a module so I just import the function when I need it)

import bpy
from mathutils import Vector

def bounds(obj, local=False):

    local_coords = obj.bound_box[:]
    om = obj.matrix_world

    if not local:    
        worldify = lambda p: om * Vector(p[:]) 
        coords = [worldify(p).to_tuple() for p in local_coords]
    else:
        coords = [p[:] for p in local_coords]

    rotated = zip(*coords[::-1])

    push_axis = []
    for (axis, _list) in zip('xyz', rotated):
        info = lambda: None
        info.max = max(_list)
        info.min = min(_list)
        info.distance = info.max - info.min
        push_axis.append(info)

    import collections

    originals = dict(zip(['x', 'y', 'z'], push_axis))

    o_details = collections.namedtuple('object_details', 'x y z')
    return o_details(**originals)

""" 
obj = bpy.context.object
object_details = bounds(obj)

a = object_details.z.max
b = object_details.z.min
c = object_details.z.distance

print(a, b, c)

"""